The invention relates to an improved cutting element or insert that may be used in machinery such as crushers, picks, grinding mills, roller cone bits, rotary fixed cutter bits, earth boring bits, percussion bits or impact bits, and drag bits. More particularly, the invention relates to inserts comprised of a cemented metal carbide segment with a non-planar interface and an abrasion resistant layer of a superhard material affixed thereto using a high pressure high temperature press apparatus. Such inserts typically comprise a superhard material formed under high temperature and pressure conditions, usually in a press apparatus designed to create such conditions, cemented to a carbide segment containing a metal binder or catalyst such as cobalt. The segment is often softer than the superhard material to which it is bound. Some examples of superhard materials that high temperature high pressure (HPHT) presses may produce and sinter include cemented ceramics, diamond, polycrystalline diamond, and cubic boron nitride. A cutting element or insert is normally fabricated by placing a cemented carbide segment into a container or cartridge with a layer of diamond crystals or grains loaded into the cartridge adjacent one face of the segment. A number of such cartridges are typically loaded into a reaction cell and placed in the high pressure high temperature press apparatus. The segments and adjacent diamond crystal layers are then compressed under HPHT conditions which promotes a sintering of the diamond grains to form the polycrystalline diamond structure. As a result, the diamond grains become mutually bonded to form a diamond layer over the substrate face, which is also bonded to the substrate face.
Such inserts are often subjected to intense forces, torques, vibration, high temperatures and temperature differentials during operation. As a result, stresses within the structure may begin to form. Drill bits for example may exhibit stresses aggravated by drilling anomalies during well boring operations such as bit whirl or spalling often resulting in delamination or fracture of the abrasive layer or carbide segment thereby reducing or eliminating the cutting element's efficacy and decreasing overall drill bit wear life. The ceramic layer of an insert sometimes delaminates from the carbide segment after the sintering process and/or during percussive and abrasive use. Damage typically found in percussive and drag bits is a result of shear failures, although non-shear modes of failure are not uncommon. The interface between the ceramic layer and carbide segment is particularly susceptible to non-shear failure modes.
U.S. Pat. No. 5,544,713 by Dennis, which is herein incorporated by reference for all that it contains, discloses a cutting element which has a metal carbide stud having a conic tip formed with a reduced diameter hemispherical outer tip end portion of said metal carbide stud.
U.S. Pat. No. 6,196,340 by Jensen, which is herein incorporated by reference for all that it contains, discloses a cutting element insert provided for use with drills used in the drilling and boring through of subterranean formations.
U.S. Pat. No. 6,258,139 by Jensen, which is herein incorporated by reference for all that it contains, discloses a cutting element, insert or compact which is provided for use with drills used in drilling and boring subterranean formation or in machining of metal, composites or wood-working.
U.S. Pat. No. 6,260,639 by Yong et al., which is herein incorporated by reference for all that it contains, discloses a cutter element for use in a drill bit, having a substrate comprising a grip portion and an extension and at least a cutting layer affixed to said substrate.
U.S. Pat. No. 6,408,959 by Bertagnolli et al., which is herein incorporated by reference for all that it contains, discloses a cutting element, insert or compact which is provided for use with drills used in the drilling and boring of subterranean formations.
U.S. Pat. No. 6,484,826 by Anderson et al., which is herein incorporated by reference for all that it contains, discloses enhanced inserts formed having a cylindrical grip and a protrusion extending from the grip.
U.S. Pat. No. 5,848,657 by Flood et al, which is herein incorporated by reference for all that it contains, discloses domed polycrystalline diamond cutting element wherein a hemispherical diamond layer is bonded to a tungsten carbide substrate, commonly referred to as a tungsten carbide stud. Broadly, the inventive cutting element includes a metal carbide stud having a proximal end adapted to be placed into a drill bit and a distal end portion. A layer of cutting polycrystalline abrasive material disposed over said distal end portion such that an annulus of metal carbide adjacent and above said drill bit is not covered by said abrasive material layer.